In mobile communications system of today there is an increasing trend of using mobile user equipment, units and telephones for other services than the traditional call and voice services. For example, a user can by means of his/her mobile telephone or associated terminal equipment, e.g. laptop or Personal Digital Assistance (FDA), access the Internet and download Web pages to the mobile user equipment. Furthermore, picture, audio, video and other data files can be transmitted between different mobile units, ordered from content or service providers and/or downloaded from Web pages. This increase in transmission of data packets and, in particular, Internet Protocol (IP) packets in the mobile communications systems, puts high demands on the processing of data packets throughout the communications system for guaranteeing satisfactory performance in terms of download times, low delay times, etc.
One way of increasing the performance of data packet transmission and processing and, thus, providing satisfactory download times for data packets in IP/Transmission Control Protocol (TCP) related mobile systems, such as General Packet Radio Service (GPRS), Enhanced GPRS (EGPRS) and Enhanced Data rates for Global Evolution (EDGE)/GPRS systems, is to provide efficient management of the data buffers that, temporarily, stores the data packets during their transmission throughout the system. In particular, the way data packets are discarded from data buffers that starts to fill up significantly impacts the end to end performance of the system.
In the prior art GPRS, EGPRS and EDGE/GPRS systems, IP packets are segmented in a Serving GPRS Support Node (SGSN) into a number of data packet segments or Logical Link Control (LLC) Packet Data Units (PDUs) before transmission to the Base Station System (BSS) and, eventually, to the relevant mobile user equipment. Due to the segmentation of IP packets, the BSS has no way of identifying those segments (LLC PDUs) in its associated data buffer that constitute a complete IP packet and, thus, cannot perform an efficient buffer management. Such a solution results in a far from satisfactory data buffer management, leading to unnecessary long download times of Web pages, files, pictures, audio, video and any other data reception that uses TCP/IP. In addition, the existing solution makes the mobile communications system sensitive to TCP/IP related parameter settings, including the employed TCP window size.